About Rationally Speaking

Rationally Speaking is a blog maintained by Prof. Massimo Pigliucci, a philosopher at the City University of New York. The blog reflects the Enlightenment figure Marquis de Condorcet's idea of what a public intellectual (yes, we know, that's such a bad word) ought to be: someone who devotes himself to "the tracking down of prejudices in the hiding places where priests, the schools, the government, and all long-established institutions had gathered and protected them." You're welcome. Please notice that the contents of this blog can be reprinted under the standard Creative Commons license.

Wednesday, September 04, 2013

Doing philosophy of science, an example

by Massimo Pigliucci

I have recently been to the European Philosophy of Science Association meeting, where my colleague Maarten Boudry and I have hosted a symposium on our recently published book on the Philosophy of Pseudoscience. I have, of course attended several other sessions and talks, as is customary on these occasions (it is also customary to enjoy the local sights, food and drinks, which I dutifully subjected myself to...).

One of these talks was entitled "Explanatory fictions and fictional explanations," by Sorin Bangu, of the University of Bergen (Norway). I want to use it as a stimulating example of one way of doing philosophy of science. Before we get into it, however, a couple of crucial caveats. As you probably know, some scientists (Lawrence Krauss immediately comes to mind as a major offender) declare philosophy of science to be useless. By this they mean useless to scientists, as apparently their limited imagination cannot conceive of how something could possibly be interesting if it doesn't contribute to science (Shakespeare, anyone? Jazz?? Soccer???). I have argued for a time now that philosophy of science is interesting in at least three senses:

1. It is a self-contained exercise in reconstructing and understanding the logic of science. (E.g., discussions of paradigms and scientific revolutions, or what you are about to read below.)

2. It is useful to science theorizing when it deals with issues at the borderlines between science and philosophy. (E.g., discussions of species concepts in biology, or of interpretations of quantum mechanics in physics.)

3. It is socially useful either as science criticism or in defense of science, whenever science either makes questionable claims or is under attack by reactionary forces. (E.g., criticism of exaggerated claims by evolutionary psychologists or fMRI enthusiasts, defense against creationism and Intelligent Design so-called "theory.")

Now, nn. 2 and 3 should be pretty obvious (ok, not to Krauss, but still). The first mode of doing philosophy of science, however, is naturally a bit more obscure to the outsider, as is the case for pretty much any intellectual endeavor (trust me, there is a lot of science being handsomely funded about which you would scratch your head and ask "who cares?"). So what follows is just a taste of philosophy of science done as an intellectual activity in its own right, aiming at reconstructing the logic of how science works. To paraphrase Groucho Marx, this is my example, if you don't like it, I have others...

The question which got Bangu started is that of how fiction can have explanatory power. And by "fiction" Bangu means pretty much any scientific theory or model, which are by definition human imaginative inventions, i.e., fictions. Scientists, of course, are fine with a positive answer to that question, indeed my bet is that they would scoff at it as a non-question. Traditionally, however, many philosophers have answered in the negative for a variety of reasons. Bangu, however, is cautiously optimistic that one can positively deal with the problem. If you are still with me, let's be clear on what exactly is being attempted here: no philosopher is suggesting that somehow scientists have been wrong all along in using "fictional" accounts in their understanding of the world. The question is logical, not practical: how can a notion that is, strictly speaking, false (a theoretical model, which is always approximate) successfully account for something that is true (the world as it really is)? If this isn't your cup of tea (fair enough), you may want to skip to a more interesting post. If your intellect is even slightly tingled, read on...

If the way I framed the issue so far still sounds bizarre (and it might), then consider clear cases in which fictions don't, in fact, explain facts. For instance: no, Santa (a fiction) didn't bring the presents (a truth) last Christmas. The general logical point is that fictions cannot explain because falsehoods do not explain. But of course in science we are talking about idealizations and approximations, not outright falsehoods, i.e., fictions "concerned with the truth." Bangu's project, then, is to unpack in what (logical) sense the Santa falsehood differs from the the type of falsehood-concerned-with-truth that scientists traffic in.

There are several ways of tackling this problem, but the particular starting point considered by Bantu is that in science not just the explanans (i.e., the thing that does the explaining) but also the explanandum (the thing to be explained) has fictional content. But, wait, what does that mean? Are we sliding toward some form of idealism in metaphysics, where reality itself is somebody's (God? The Big Programmer in the Sky?) mental construction? Nothing of the sort (besides, an idealist would simply reply that mental constructions are real, just not physically so!). Instead, Bantu reminded us that data - the raw starting point of any scientific analysis - is immediately shaped by scientists into phenomena, that is, phenomena are constructed from data, they are not "out there," they are posited. To put it into more formal language: fictions in the explananda is what allows the successful use of fictions in the explanans. Bantu refers to this idea as the "Monopoly principle": you can't buy real property with fictional money (well, unless you are Goldman Sachs, of course), but there is no problem in buying fictional property with fictional money...

Okay, enough with the preliminaries, let's consider an actual example of scientific practice. The one Bantu picked was the answer to the deceptively simple question: why does water boil? The explanandum is water's (or other substances) capacity to undergo "phase transitions." The explanans these days is couched in terms of statistical mechanics. In current practice, a phase transition can be explained by invoking a role for (mathematical) singularities of the function describing the temperature curve of the system transitioning between phases, assuming that the system contains an infinite number of particles. But singularities are "fictional," and of course no real system actually contains an infinite number of particles. Nevertheless, the role of singularities is to represent the phenomenon to be explained, and they do a very good job at it. Moreover, physicists - at least for now - simply do not have a definition of phase transition that doesn't invoke singularities/infinities.

There are of course a number of further issues raised by Bantu's talk. I have already mentioned that a scientist would immediately point out the difference between idealizations and fictions. It turns out, however, that this only kicks the can a bit further down the road without solving the problem, since now we would have to unpack the (perceived) difference between idealizations and fictions. One could, for instance, think of idealizations as a sub-class of fictions; or maybe one can cash out the idea of idealization in terms of verisimilitude (truth-likeness, which is another philosophically more-difficult-than-you-think idea). And of course there is the broader question of how widely applicable Bantu's account of the relationship between truth and fiction in science actually is: are all scientific theories "fictional" in the philosophical sense of the term?

However you go about it, two things are important to keep in mind: a) no, this isn't the type of philosophy of science that should concern or worry scientists (who can go on using their tools without having to deal with how those tools logically work); but b) yes, this is an interesting intellectual puzzle in its own right, if your intellectual curiosity happens to be stimulated by logical puzzles and epistemic problems. If not, you can always go back to types 2 and 3 philosophy of science described above.

Say there are 10 contending hypotheses. BHS asserts that we must equally apportion initial allocated Certainty (technically called informatic entropy) between all proposed hypotheses. Thus h0 is given certainty 0.1, h1 certainty 0.1, and so on until we attribute h9 with certainty = 0.1.

Experiments are then undertaken, and so some hypotheses acquire additional confirming evidence, and others may acquire none at all, or even disconfirming evidence.

At a time later we may see the initial certainty profile evolve to : h0 = 0.7, h1 = h2 = 0.1, h3 = 0.8, h4 = 0.1, and so on. Note that the sum of all certainties does not have to equal 1.0, as is so for probabilities.

Clearly h0 and h3, as they stand are (almost) equally good hypotheses. How do we choose between equally GOOD competing explanations?There are several strategies used to resolve this contest :1. We say we “don’t know” which hypothesis is best, and use either hypothesis h0 or h3 as suits circumstances.2. We suspend implementing any hypothesis, and say “more evidence is needed.”3. We demand that any successful hypothesis must surpass its competitors by a large amount (e.g. the “5 Sigma Proof”, in Physics).

Note these logic “certainties” do not at all correspond to the “probabilities” of gaming theory or statistics.

Certainty measures the degree of belief in a probability outcome, using either 0 – 100% certainty, or (-)100 certainty – 0 – (+)100% certainty; whereas Probability measures how often a particular outcome occurs, as a number from 0 – 100%. Each and every time a probability figure disagrees with factual reality, then the certainty in that probability is reduced. Certainty incorporates past performance, whereas Probability (e.g. the tossing of a coin) is said to be the same with each test, no matter how many heads or tails appeared in the past.

A very rough analogy may help understanding here: In acoustic engineering, humans ears can tolerate an acoustic loudness level from : 10dB (@2KHz) to 110dB (@2 Khz). But if the sound is speech or music, then no matter how loud/quiet this sound may be, it becomes incoherent if the Signal-to-Noise-Ratio falls below approximately 5dB. One may crudely analogise Probability to Loudness, and Certainty to Signal-to-Noise-Ratio.-

The otherwise perceptive Richard Feynman supposedly said something like "Philosophy of science is as useful to scientists as ornithology is to birds." Would that include the ornithology that lead to the banning of DDT and the great rebound in the bald eagle population?

It's probably true that the day-to-day work of scientists doesn't depend much on the philosophy of science (unless they are trying to figure out how, exactly, to approach a novel and difficult empirical problem) but when they sit down to ... you know ... think about what their results actually mean, they are, whether or not they know it, philosophizing.

I have a problem with the notion that scientific theories are necessarily fictional. I see no logical contradiction in the idea of having a perfectly true scientific theory which is perfectly correct.

That said, I'm not arguing that any particular scientific theory we currently use is an example of this (although I wouldn't be surprised if a rigorous defence could not be mounted of the truth of some existing scientific statements).

Also, you stated that no physical system can have an infinite number of particles. How about the universe? It seems to me to be quite reasonable to hypothesise that the universe might be infinite in extent, with an infinite amount of matter. Does this strike you as incoherent or is this simply not what you meant by a physical system?

On the main issues of your post, I don't really see the problem. As with most things, I think there's a continuum, in this case between fictional and accurate, as you hint at with your mention of verisimilitude or truth-likeness. The degree to which a theory is useful corresponds to how accurate it is. This seems not to be too mysterious to me, but I guess I'll have to read that SEP article on truth-likeness when I have a chance in order to appreciate the difficulties which currently elude me.

As a follow up, it strikes me that the problem you raise is not in any way characteristic of science in particular.

Potentially, almost all statements are fictional, but they may still be useful.

For example, if I say "You are a philosopher", that may appear to be correct, but it presupposes the existence of entities which don't fundamentally exist, namely "you" and the concept of a "philosopher".

"You" don't really exist because "you" are just a convenient abstraction used to describe a mass of atoms temporarily associated and acting in concert, and even those atoms don't exist because they're all just fluctuations in the quantum Hilbert space or what have you.

This seems to me to be at least as reasonable as the proposition that gravity is only a useful fiction.

"I have already mentioned that a scientist would immediately point out the difference between idealizations and fictions..."

This may not solve the problem, but doesn't it change it to something utterly different so that Father Christmas-type examples are just no longer relevant, and the very use of the word 'fiction' becomes misleading or at least problematic.

Also, informal concepts like explanation seem to be intrinsically flexible and vague. Perhaps the word only really works well in cases of relatively simple explanations which are intuitively satisfying, like explaining someone's behaviour ("He was angry about such and such...") or simple explanations (scientifically-based or not) of phenomena such as one might give to children (like explaining a rainbow). And as the science becomes more advanced, mathematicized etc., theories just don't 'explain' in the same way, and are more about modeling and predicting.

I think of a phase transition as when you cross a fixed point in the RG flow (I am an condensed matter experimentalist). In an infinite system, this produces singularities, but in a finite system, the phase transition is still well-defined. Of course, this is just a deeper fiction, and I am merely nitpicking.

What's interesting to me is that sometimes "fictions" are necessary in science for it to really count as an explanation. You could run a massive and precise simulation of a material, and show that superconductivity exists in the simulation, but that doesn't answer why there exists superconductivity. When we ask "why", what we're really asking for is a good fictional account.

I think it seems necessary to frame our conceptions in order to come to approach useful or instrumental understanding. For example, we conceptualize chairs and ourselves and other persons as individual entities seemingly separate or independent from the finer grained relations taking place at sub-atomic levels. This allows us to functionally interact with other persons and sit in chairs. But any frame of reference must to a degree be a fictional abstraction from the underlying ontology.

On this I would agree with Krauss, most of the work devoted to philosophy of science is irrelevant (and could be better framed in popular science or as contemporary history of science). However I guess there are meanigfull contributions (the work of Susan Haack comes to my mind).

> but doesn't it change it to something utterly different so that Father Christmas-type examples are just no longer relevant, and the very use of the word 'fiction' becomes misleading or at least problematic. <

The Father Christmas example was an extreme one to make the point. No matter how you look at it, scientific theories are “fictional” in an interesting sense. (One may not want to use that word, if one associates a lower status to fiction, but the concept remains.)

> as the science becomes more advanced, mathematicized etc., theories just don't 'explain' in the same way, and are more about modeling and predicting. <

Or sometimes just modeling, with little predictive ability (string theory?).

miller,

> In an infinite system, this produces singularities, but in a finite system, the phase transition is still well-defined. Of course, this is just a deeper fiction, and I am merely nitpicking <

But the point seems to be that theoretical modeling of phase transitions can’t do without singularities, at the least at the moment. I’m not a physicist, but I’ve asked, and that seems to be the case.

Disagreeable,

> I see no logical contradiction in the idea of having a perfectly true scientific theory which is perfectly correct. <

Maybe, though I’m not sure what that means, exactly. We would still left with the idea that some scientific theories are fictional, and yet useful. So the problem would be more limited in scope (some theories, instead of all theories) but still present.

> Also, you stated that no physical system can have an infinite number of particles. How about the universe? <

Not sure. I think the consensus in cosmology is that the universe is finite. But even within an infinite universe you still have a (infinite?) number of finite systems for science to contend with.

> I think there's a continuum, in this case between fictional and accurate <

Are “fictional” and “accurate” on the same continuum? I’m not sure.

> seems not to be too mysterious to me, but I guess I'll have to read that SEP article on truth-likeness when I have a chance in order to appreciate the difficulties which currently elude me. <

Yeah, truth-likeness is a very intuitive concept, until one realizes that in order to measure how close you are to the truth it would seem that you would already have to know where the truth lies. There are ways around this, but they ain’t straightforward.

> it strikes me that the problem you raise is not in any way characteristic of science in particular. Potentially, almost all statements are fictional, but they may still be useful. <

Yes, though science seems to rely on particularly sophisticated fictions. At any rate, remember that nobody is doubting that scientific “fictions” are useful. It’s a question of how do they work logically. (And I beg to differ about my own existence: I do exist, you simply redefine your concept of me in your comment, you didn’t show that I don’t exist. But that’s a different discussion.)

Vasco,

> On this I would agree with Krauss, most of the work devoted to philosophy of science is irrelevant <

Sorry that you completely missed the point of the post. Oh well, I tried.

Don't take my comment too seriously (just a litle provocation). However, as John Pieret above quotes Feinman, "philosophy of science is as useful to scientists as ornithology is to birds" and that is that. It could be different, however scientists don´t have that perception, is it their fault or does the problem stands on the side of the philosophy of science?

Besides the demarcation problem is meaningless to science (although it may be relevant to politics, ideological agendas, popular science, or to the chase of scientific heresies). The fascination of philosophers of science for the demarcation problem is in itself fascinating (and maybe it desearves to be framed in the light of evolutionary psycophilosophy).

That said I have to acknowledge that philosophy of sciences can address a variety of issues in science (from epistemological aspects to the meaning and value of new findings and challeges science reveals). In this respect I must confess that the dialogue between science and philosophy is not so easy and natural as one could expect.

"So the problem would be more limited in scope (some theories, instead of all theories) but still present."

I agree.

"I think the consensus in cosmology is that the universe is finite."

I think the consensus in cosmology is that the answer is unknown, and perhaps unknowable. It seems we could only ever know the answer if the universe is finite and below a certain size. So far, it seems that the universe is at least big enough for it to be empirically impossible to determine if it is finite or infinite. The idea of an infinite universe is certainly not ruled out, and my understanding is that most cosmologists are open to the idea.

"Are “fictional” and “accurate” on the same continuum? I’m not sure."

Well, perhaps I didn't explain myself well. I suppose I'm talking about a continuum of "truthlikeness", with outright falsehood on one end and perfect accuracy on the other. Fiction is then everything that is not at the extreme accurate end. The predictive power of a theory is on a corresponding continuum, from uselessness to perfection. The position of a theory on this latter spectrum is largely determined by the truthlikeness of its statements and models.

This seems relatively self-evident to me, and means that I fail to see the problem with the topic under discussion.

"I do exist"

I have no issue with that. My point is that if we doubt the fundamental existence of the entities proposed by scientific theories, e.g. quarks, protons, atoms, gravity, energy, etc, then we could similarly doubt the existence of any high-level object, including ourselves.

I agree that you exist. But I also think, on the same grounds, that those scientific entities exist. As such, perhaps the word "fictional" is not the best choice.

Don't get me wrong. I appreciate the importance of philosophy. I wish we scientists would learn more philosophy of science during our training. I wish I had had more philosophy of science during my studies. The post is instructive.

But so help me, this comment tread immediately ticks me off.

According to John Pieret, I am doing philosophy when I think, does this P value mean that there is no evidence for a significantly higher diversity than expected? So apparently every activity that involves thinking is philosophy, but as I know from experience with these discussions, an activity that involves generalizations from empirical data is only science under extremely narrowly defined conditions, such as when it happens in a special building where everybody has to wear a lab coat. Because expanding the definition of science to about a tenth of how wide the definition of philosophy preferred here is would be scientism. Talk about double standards.

And according to MJA, science gave us Fukushima. Where to start?

Did Charles Darwin, Alfred Wegener or Albert Einstein give us Fukushima? No? But they are scientists, aren't they? Funny that.

But okay, there are nuclear scientists. So, did Marie Curie build Fukushima? Did Otto Hahn finance its construction? Did Leó Szilárd write and pass the legislation regulating the use of nuclear energy? Did any of them advise Tepco specifically to build the plant in a spot that is subject to earthquakes and tsunamis, and did they instruct the company to build insufficient fail-safe systems?

When the first nuclear scientists made the first steps towards understanding how a stable nuclear reaction could be achieved, would you say it would have been their moral duty to realize precisely what would happen decades later, foresee all the inherent dangers, assume the worst of voters, engineers, managers and politicians, and destroy all their results and notes at the earliest juncture while naively assuming that nobody else would invent the same thing instead?

Ye gods. Why does "science" make such a convenient bogeyman to so many people? Ultimately science it is nothing but the use of empirical evidence and reason to figure out how the world works. You can do it, I can do it, that is why there is "citizen science". It is a tool that gives us more options, but which option we chose is still up to us, collectively.

Seriously, one cannot coherently argue that Harris is *wrong* for claiming that science determines moral decisions and that it is the fault of science whenever a stupid decision has been made. Pick one.

Maybe I am wrong, science didn't create nuclear fission, it was the mating butterflies again. And the filtering of reality is called denial DM, that radiation pouring into the Pacific if you dare to look, is real. I hope the butterflies get a handle on it soon! =

> as John Pieret above quotes Feinman, "philosophy of science is as useful to scientists as ornithology is to birds" and that is that. It could be different, however scientists don´t have that perception, is it their fault or does the problem stands on the side of the philosophy of science? <

That much quoted quip by Feynman, frankly, shows how idiotic even very very smart people can be. Feynman, like Krauss, Hawking, and a number of others, simply doesn't know what he is talking about, and likely has never read a paper in philosophy of science. It's anti-intellectualism at the almost pure state, and what makes it maddening is that it comes from highly visible intellectuals. This is the scientific counterpart of what C.P. Snow was complaining about more than half a century ago: cultured people who think that everyone ought to read Shakespeare, but who scoff at the second principle of thermodynamics.

> Besides the demarcation problem is meaningless to science <

The hell it is. It has very practical consequences on people's understanding of science, science policy, and science funding. That ought to be meaningful to practicing scientists.

> That said I have to acknowledge that philosophy of sciences can address a variety of issues in science <

Indeed. And I really don't see the point of all this acrimony, which usually comes from scientists.

Alex,

I agree with your comments, but I found this a bit ironic:

> So apparently every activity that involves thinking is philosophy, but as I know from experience with these discussions, an activity that involves generalizations from empirical data is only science under extremely narrowly defined conditions <

So now you see what it feels like when someone is unreasonably expanding their own domain, yes? ;-)

And while I agree with your (frustrated) response to MJA, this seems to me a non-sequitur:

> one cannot coherently argue that Harris is *wrong* for claiming that science determines moral decisions and that it is the fault of science whenever a stupid decision has been made. Pick one. <

My (naive) understanding is that a universe that had a beginning (Big Bang) cannot be infinite, though it can expand indefinitely. That distinction is crucial to our sub-discussion.

> Fiction is then everything that is not at the extreme accurate end. The predictive power of a theory is on a corresponding continuum, from uselessness to perfection. <

Right, I suspected you interpreted the term "fiction" here as derogatory. That was definitely not the intention of the author of the paper I commented on.

> I agree that you exist. But I also think, on the same grounds, that those scientific entities exist. <

But the question is: how do we know? We don't have direct access to those entities, so we postulate something we call "quark," "electron" and so on, which are then best thought as theoretical entities ("fictional" in the neutral sense of the term) that are meant to account for the empirical phenomena we observe.

>My (naive) understanding is that a universe that had a beginning (Big Bang) cannot be infinite, though it can expand indefinitely.<

This is indeed a subdiscussion, but an interesting one. It might be worthy of an article some day, because if it is empirically undeterminable then perhaps philosophy may have something to offer (e.g. on the topic of whether it is coherent to propose an infinite amount of stuff).

But to answer your point, I am sorry to say that I think your understanding it is indeed naive. My own understanding may be only slightly less so, but I feel I can confidently assert that an infinite universe is compatible with both indefinite expansion and a big bang singularity.

I am not simply saying that it can expand indefinitely, I am saying that it is possible for it to be infinite in extent at all points in time, even at the singularity.

In an infinite universe, the big bang singularity is not a single point. It consists of the whole infinite universe. It's still a singularity because the universe is infinitely dense.

This infinite universe can then expand indefinitely as everything flies away from everything else and the universe becomes less dense.

You could visualise the stuff in the universe as analogous to the integers on the numberline, and visualise the expansion as multiplying all the numbers on the numberline by a constant analogous to time.

So, at t=0, there are an infinite number of integers but they are all multiplied so as to be equal to zero and so are infinitely close together. (The analogy doesn't really make much sense here because a singularity leads to logical contradictions and so there may never have been one - see loop quantum gravity).

At t=0.00001 they are spread out, with an infinite number of values, but it's quite dense. At t=1000, it's not nearly as dense. The "universe" is infinite but expanding.

>I suspected you interpreted the term "fiction" here as derogatory<

No, I don't think so. I interpreted it as meaning not 100% perfectly accurate.

"We don't have direct access to those entities"

Fair point. You do after all have direct access to yourself. But you don't have direct access to other people. You can only observe them by detecting photons bouncing off them, or by detecting nerve impulses from your fingers as you reach out to touch. I presume you think that other people exist, so why are electrons fictions?

I was assuming that electrons have a 'fictional' status simply because they do not possess the same ontological status as, say, tables and chairs. I don't think Massimo was implying electrons are complete fictions cooked up in the mind of physicists but rather that we do not possess direct access to them. Perhaps there is more to it?

I'd say if anything that electrons are even more ontologically sound than tables and chairs. Tables and chairs are abstractions used to describe loosely-defined amalgamations of particles such as electrons.

I don't get why direct access is so important, especially for ontology (it may be for epistemology). As I tried to explain, I don't think we have direct access to anything except perhaps our own minds.

To my mind, there is no fundamental difference between the way that I infer that the table in front of me exists and the way that a scientist infers that an electron exists. In each case, we are interpreting our percepts and trying to come up with a model of reality that matches what we perceive.

Of course, it takes considerably more ingenuity to do that in the case of electrons, but I still think that both cases are instances of interpretation rather than "direct access".

Fine, we infer the existence of electrons in a different way than we infer the existence of tables and chairs. Are you implying that I'm more "safe" and "correct" when I describe characteristics of electrons than when describing tables and chairs? For me, perhaps I do not have direct access to tables and chairs in the technical sense (inferring existence) but don't I have less direct access to electrons which I cannot see/feel?

I'm actually arguing that the way we infer the existence of electrons is fundamentally no different to the way we infer the existence of tables and chairs.

In this view, there is no qualitative difference in the ways we perceive them, but there is a quantitative difference. So, I certainly agree that our access to electrons is less direct, but I don't think that this means we can call electrons "fictional" while maintaining that tables are "real".

In particular, I'm not sure how safe or correct you are in judging the qualities of tables. A table seems solid and heavy, yet it is mostly empty space and entirely permeable to small particles such as neutrinos. There's also the weirdness of quantum mechanics which tells us that reality itself (tables included) is fundamentally very different from how it appears.

The mental model we have of a table is therefore an abstraction, a simplification of an object of enormous counter-intuitive complexity. The concept of "table" you hold in your mind is therefore just as fictional as any scientific model.

The problem with that quote from Feynman is that it describes quite well the perception that scientists have in relation to philosophy of science.It may be that scientists are somewhat arrogant, too enclosed in their own field of research and dismissive of other domains of knowledge (such as philosophy). I agree with you on this. However I think this explains a part of the problem, the other is that philosophers of science have a strong tendency to present themselves as irrelevant to science, namely in their propensity to adopt a position of oracles in the name of science (there is some absurdity in this pretention). Here we disagree, I guess.

I agree that tables & chairs are heuristic constructions that approximate the finer grained models we also construct. From a private subjective point of view tables and chairs seem less abstract (more real?) then fermions & bosons.

From an objective (or inter-subjective) point of view fermions & bosons & their relations would seem to be more fundamental then tables & chairs. This is why I take the position that the two points of view are complementary. We should understand that each point of view is in some sense partial (fictional), neither represents ultimate truth, yet together I think they help get closer to the underlying reality.

The measure of an electron is uncertain or only probable at best. And probability is a pseudoscience of everything but the absolute. Then what you may ask would science be without their own uncertainty, without the pseudo of scientific measure?The answer is scientifically philosophical, it is simply the elegant, absolute, certainty of truth.

> This infinite universe can then expand indefinitely as everything flies away from everything else and the universe becomes less dense. <

But that, if it makes sense has nothing to do with our discussion. We were talking about whether there can be an infinite number of objects in the universe. It seems to me that the answer is clearly not, if the universe had a beginning and objects (atoms, stars, etc.) were formed afterwards in a finite period of time.

> I interpreted it as meaning not 100% perfectly accurate. <

That’s still not what the author meant. A perfectly accurate theory (whatever that means) is still a “fiction,” in the sense of being an entity created by the human mind, not a thing in the universe.

> you don't have direct access to other people <

Not even close to the degree to which we don’t have access to electrons. We can’t see them even in principle, and they are “particles” only in a very metaphorical sense of the terms. Very different from seeing people and describe them qua biological organisms.

Stewey,

> I don't think Massimo was implying electrons are complete fictions cooked up in the mind of physicists but rather that we do not possess direct access to them. <

Actually, quite close. Electrons are theoretical unobservables (in principle) that are “made up” by physicists to account for a certain number of observable empirical effects. So in this sense they are highly “fictional.” But, again, in this context neither “fictional” nor “made up” are to be understood in a derogatory manner.

Agreed, but it seemed like Disagreeable Me was implying that intuitive appearances to the contrary, the ontological status of electrons is more secure and more precisely defined than that of tables and chairs which doesn't make sense to me given that physicists can't really tell you what an electron "is" in any meaningful (intuitive) sense.

But that gets me to another question- who determines the ontological status of, well, anything really? I assumed (naively?) that tables and chairs "exist" but Disagreeable doesn't appear to grant "existence" the same way I do. This is all very confusing to me!

"But that, if it makes sense has nothing to do with our discussion. We were talking about whether there can be an infinite number of objects in the universe. It seems to me that the answer is clearly not, if the universe had a beginning and objects (atoms, stars, etc.) were formed afterwards in a finite period of time."

I think you are certainly wrong on this, and I believe cosmologists would back me up. If the universe is infinite in extent, then there is an infinite number of objects in the universe.

There are a couple of different ways to explain why, with different levels of technical detail.

Firstly, I would ask you to imagine what it might mean to think that the universe is infinite in extent but having a finite number of objects. This would necessarily imply that the universe is essentially empty.

And yet we see matter all around us, so apparently we exist in (one of a number of?) very special localised regions of activity. This goes against the intuitions of most cosmologists that the universe is pretty homogenous at a large scale.

In order to understand why we expect the universe to be homogenous, we ought to remember that the standard view of the creation of particles is that they arise spontaneously out of the quantum structure of the universe. If the universe is infinite in extent, this quantum structure is everywhere and without bound.

You can therefore think of space as a infinite matrix of matter factories, and if we have an infinite number of factories then we can indeed have an infinite number of objects created in a finite time.

No objection there. What I meant to say is that blaming science for everything bad that is happening since about 1850 presupposes that science demands everything that is invented also be realized.

But that is just plain wrong; science does not demand anything, neither whatever Harris thinks he can demonstrate nor the building of a power plant. The best science qua science can do is: If you desire X, then you can achieve that best by doing Y, but be aware of possible downside Z.

Whether we should desire X and whether we should consider Z acceptable is still beyond the realm science and entirely dependent on our subjective values, whether Z is a surveillance state or the risk of a meltdown. In that sense, there is a clear parallel.

There seems to be some confusion regarding the big bang and/or the singularity. As Disagreeable Me notes the term singularity is not really a point per se. It's our attempt to describe how our universe started in light of the observation that the universe is expanding. Space doesn't really need to expand into anything except itself. So what some say is that space began to stretch. But it's hard to grasp this without resorting to the notion of a "point" or singularity. Physicists know what they mean by it: a kind of explanatory roadblock. (In the 60's, this was known as something that blows one's mind.) If space is infinite it can be conceived of as very small scale but still be infinite. (This too I think was suggested by Disagreeable Me and correctly so.) Since the models and math break down at what we call, for lack of anything better, the beginning. You might call this a fiction too. At any rate, as Disagreeable Me suggests, the debate about whether the universe is finite or infinite continues, and there is even talk about eternity entering the picture again.

> The problem with that quote from Feynman is that it describes quite well the perception that scientists have in relation to philosophy of science. <

Perhaps, but that’s their limitation, not philosophy’s. Again, just in the same way in which Snow’s humanist colleagues’ lack of appreciation for the second principle of thermodynamics was the result of their narrow mindedness.

> philosophers of science have a strong tendency to present themselves as irrelevant to science, namely in their propensity to adopt a position of oracles in the name of science <

I see philosophers of science everyday, and frankly I haven’t noticed this. They are a bunch made of people with a high respect for science, who are genuinely curious about how it works and why it fails, when it does.

Seth,

> I agree that tables & chairs are heuristic constructions that approximate the finer grained models we also construct. <

I actually disagree. As Ladyman and Ross nicely put it in their Every Thing Must Go, it’s time to stop thinking that tables and chairs (and all other macro-objects) don’t “really” exist. They are discrete patterns of organization of matter, *made of* more fundamental stuff. It is a crucial ontological mistake to say that just because they are made of X then they are nothing but X. Imagine saying that you don’t really live in a house, because houses don’t exist, they are just piles of bricks...

> From an objective (or inter-subjective) point of view fermions & bosons & their relations would seem to be more fundamental then tables & chairs. <

Except that fermions and bosons are actually theoretical constructs, unobservable in principle, that physicists deploy to make sense of certain empirical data. Their ontological status, therefore, is far more complicated than that of chairs and tables.

Disagreeable,

> You can therefore think of space as a infinite matrix of matter factories, and if we have an infinite number of factories then we can indeed have an infinite number of objects created in a finite time. <

Even so, it still doesn’t get to our original discussion. Let’s assume for the sake of argument that the universe is infinite, and that there is continuous production of particles at the quantum level. Our discussion was about visible or quasi-visible objects, like water molecules, chairs, stars, etc. Surely you agree that there is a finite number of those? Because that’s all it’s needed for the author of the talk’s argument to go through.

Sorry, but I think you're still labouring under some false assumptions. Don't take my word for it, check with any reputable cosmologist friends you may have if you're still in doubt.

I'm not so much talking about the continuous production of virtual particles we see in the universe today. I'm talking about the original production at or just after the Big Bang of the primordial particles that went on to become atoms, molecules, gas clouds, stars, planets, people and ultimately chairs and tables.

In an infinite universe, these original particles would have been created everywhere throughout space at the same time and in parallel, so infinite space does indeed imply an infinite number of tangible objects.

Now, if you confirm the truth of this with a cosmologist who you trust, I think there is an interesting philosophical question to ask about whether this is coherent or not. I think it is, but I have seen philosophical arguments that an infinite number of objects is somehow incoherent.

If those arguments are correct (which I doubt), then we have philosophical grounds to doubt that the universe is infinite even if the question is empirically undecidable.

I acknowledge that my personal view may be somewhat unfair and it makes no sense to insist arguing with you (in this you must have access to a larger variety of information and a better understanding of the problem). I will try to educate myself.

'I actually disagree. As Ladyman and Ross nicely put it in their Every Thing Must Go, it’s time to stop thinking that tables and chairs (and all other macro-objects) don’t “really” exist. They are discrete patterns of organization of matter, *made of* more fundamental stuff. It is a crucial ontological mistake to say that just because they are made of X then they are nothing but X. Imagine saying that you don’t really live in a house, because houses don’t exist, they are just piles of bricks...'

I wouldn't say tables & chairs don't exist. Just that they aren't fundamental from an objective particle physics reference frame. I am arguing that we need to also include the subjective view (from which they do seem to exist).

'Except that fermions and bosons are actually theoretical constructs, unobservable in principle, that physicists deploy to make sense of certain empirical data. Their ontological status, therefore, is far more complicated than that of chairs and tables.'

I don't think either the constructs of fermions & bosons or subjective observations of chairs & tables can lay claim to represent complete ontological truth. I agree we shouldn't discard the subjective experience of tables & chairs just as we shouldn't try to eliminate conscious subjective experience by saying it is all just neurons firing in the brain.

My view is that there is an ontology out there of which we have partial complementary ways of accessing. I think it is important to recognize the incompleteness of any particular frame of reference.

> Sorry, but I think you're still labouring under some false assumptions. <

Maybe I am, but please answer a direct question: do you think there are infinite number of stars (or chairs, or whatever) in the universe? Because that’s what’s at stake in this discussion, not the infinity of the universe per se. (Also, I checked around, and the latest isn’t encouraging for infinity: http://goo.gl/BrSXgK)

Seth,

> I wouldn't say tables & chairs don't exist. Just that they aren't fundamental from an objective particle physics reference frame. I am arguing that we need to also include the subjective view (from which they do seem to exist). <

I don’t think we are very far, except that I reject talk of “fundamental” in the sense of “more important.” Our “subjective” view is actually ontologically more salient than the particle view, since “particles” are theoretical constructs, not solid objects.

> do you think there are infinite number of stars (or chairs, or whatever) in the universe?<

If I had to bet, I would put my money on there being an infinite number of stars, yes, because I suspect on philosophical grounds that space is infinite in extent. I am not at all sure about this, however. Perhaps 51% sure.

I am however 99.9% certain that infinite space implies infinite stars, and I see no reason to think that infinite space is incoherent, although perhaps I could be proven wrong on philosophical grounds.

>(Also, I checked around, and the latest isn’t encouraging for infinity: http://goo.gl/BrSXgK)<

It seems that the headline of the article is misleading, probably the journalist's fault. According to the text of the article, the physicists are proposing that the universe has no infinite future, and that it may be wiped out by a catastrophic event. They make no comment on whether it is infinite in spatial extent. As far as I know, this really is an open question.

Yeah, that linked article was off topic. Do you have a link to an article about the infinity (or not) of the universe that I can read during the weekend? I searched, but I didn't find anything that really satisfied me (either too short or generic pieces or things that had little to do with the question at hand). Thanks.

I'm not working from any specific source, just general understanding of the field gleaned from years of pop science books and youtube videos, etc. I'll post some links here that seem pertinent based off Google searches I'm doing as I write.

I think you're not going to find much discussion of the idea that an infinite universe entails an infinite number of stars, because that's generally assumed or taken for granted. If you think about it it is implied by the statement that the universe is homogenous, which you will find many cosmologists asserting.

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This interview has a nice overview of some of the issues, although it's a bit out of date. It refers to a future experiment which may provide evidence that the universe may be infinite. That experiment (WMAP) subsequently came out looking good for infinity.

Also, important to understand what is meant by a flat universe. The universe appears to be flat, to within margins of experimental error. If it is actually flat (or negatively curved), then it is infinite.

This rather long article discusses some of the unintuitive consequences of an infinite universe or universes, although it's mostly concerned with Boltzmann brains and parallel universes which are probably only of peripheral concern, though interesting in their own right:

Finally, if you really want a good overview of the whole thing, I must regretfully advise you to read A Universe From Nothing by Lawrence Krauss. Even if he is unreasonably dismissive of philosophy and generally far too scientistic, he is a good cosmologist, writes well and knows what he's talking about within his domain.

thanks, nice to see that my google searches turned out pretty much the same stuff! I have nothing against Krauss as a cosmologist. I just can't stand his clearly uninformed and pompous talk about philosophy. Will check some of these links.

But actually, I think this paper by Max Tegmark is an excellent resource. Please read the section on Level I Parallel Universes (which is basically the idea that if the universe is infinite then remote parts of the universe are causally disconnected from us and so effectively not in our subjective universe).

Massimo-I don’t think we are very far, except that I reject talk of “fundamental” in the sense of “more important.” Our “subjective” view is actually ontologically more salient than the particle view, since “particles” are theoretical constructs, not solid objects.

Thanks - I qualified my use of the term 'fundamental' by adding 'from an objective particle physics reference frame'. Which perspective is more important I think would depend on the specific ontological question or claim being addressed, and neither perspective as we seem to agree should be completely ignored.